// RainForest hash algorithm - CRC32 calculation
// Author: Bill Schneider
// Date: Feb 13th, 2018

#include <stdint.h>

#ifdef _MSC_VER 
#define inline __inline
#endif

#if defined(RF_NOASM) || !defined(__aarch64__) || !defined(__ARM_FEATURE_CRC32)
// crc32 lookup tables
static const uint32_t rf_crc32_table[256] = {
	/* 0x00 */ 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
	/* 0x04 */ 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
	/* 0x08 */ 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
	/* 0x0c */ 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
	/* 0x10 */ 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
	/* 0x14 */ 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
	/* 0x18 */ 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
	/* 0x1c */ 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
	/* 0x20 */ 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
	/* 0x24 */ 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
	/* 0x28 */ 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
	/* 0x2c */ 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
	/* 0x30 */ 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
	/* 0x34 */ 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
	/* 0x38 */ 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	/* 0x3c */ 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
	/* 0x40 */ 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
	/* 0x44 */ 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
	/* 0x48 */ 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
	/* 0x4c */ 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
	/* 0x50 */ 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
	/* 0x54 */ 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
	/* 0x58 */ 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
	/* 0x5c */ 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
	/* 0x60 */ 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
	/* 0x64 */ 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
	/* 0x68 */ 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
	/* 0x6c */ 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
	/* 0x70 */ 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
	/* 0x74 */ 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	/* 0x78 */ 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
	/* 0x7c */ 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
	/* 0x80 */ 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
	/* 0x84 */ 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
	/* 0x88 */ 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
	/* 0x8c */ 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
	/* 0x90 */ 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
	/* 0x94 */ 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
	/* 0x98 */ 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
	/* 0x9c */ 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
	/* 0xa0 */ 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
	/* 0xa4 */ 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
	/* 0xa8 */ 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
	/* 0xac */ 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
	/* 0xb0 */ 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	/* 0xb4 */ 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
	/* 0xb8 */ 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
	/* 0xbc */ 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
	/* 0xc0 */ 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
	/* 0xc4 */ 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
	/* 0xc8 */ 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
	/* 0xcc */ 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
	/* 0xd0 */ 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
	/* 0xd4 */ 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
	/* 0xd8 */ 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
	/* 0xdc */ 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
	/* 0xe0 */ 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
	/* 0xe4 */ 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
	/* 0xe8 */ 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
	/* 0xec */ 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	/* 0xf0 */ 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
	/* 0xf4 */ 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
	/* 0xf8 */ 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
	/* 0xfc */ 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};
#endif

// compute the crc32 of 32-bit message _msg_ from previous crc _crc_.
// build with -mcpu=cortex-a53+crc to enable native CRC instruction on ARM
static inline uint32_t rf_crc32_32(uint32_t crc, uint32_t msg)
{
#if !defined(RF_NOASM) && defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
	__asm__("crc32w %w0,%w0,%w1\n" : "+r"(crc) : "r"(msg));
#else
	crc = crc ^ msg;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
#endif
	return crc;
}

static inline uint32_t rf_crc32_24(uint32_t crc, uint32_t msg)
{
#if !defined(RF_NOASM) && defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
	__asm__("crc32b %w0,%w0,%w1\n" : "+r"(crc) : "r"(msg));
	__asm__("crc32h %w0,%w0,%w1\n" : "+r"(crc) : "r"(msg >> 8));
#else
	crc = crc ^ msg;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
#endif
	return crc;
}

static inline uint32_t rf_crc32_16(uint32_t crc, uint32_t msg)
{
#if !defined(RF_NOASM) && defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
	__asm__("crc32h %w0,%w0,%w1\n" : "+r"(crc) : "r"(msg));
#else
	crc = crc ^ msg;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
#endif
	return crc;
}

static inline uint32_t rf_crc32_8(uint32_t crc, uint32_t msg)
{
#if !defined(RF_NOASM) && defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
	__asm__("crc32b %w0,%w0,%w1\n" : "+r"(crc) : "r"(msg));
#else
	crc = crc ^ msg;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
#endif
	return crc;
}

/* returns a CRC32 of message <msg> from previous <crc>; the 32 highest bits
 * are zeroed.
 */
static inline uint64_t rf_crc32_64(uint32_t crc, uint64_t msg)
{
#if !defined(RF_NOASM) && defined(__aarch64__) && defined(__ARM_FEATURE_CRC32)
	uint64_t crc64 = crc;

	__asm__("crc32x %w0,%w0,%x2\n" : "=r"(crc64) : "0"(crc), "r"(msg));
	return crc64;
#else
	crc ^= (uint32_t)msg;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);

	crc ^= msg >> 32;
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	crc = rf_crc32_table[crc & 0xff] ^ (crc >> 8);
	return crc;
#endif
}

/* performs a CRC32 on a memory area */
static inline uint32_t rf_crc32_mem(uint32_t crc, const void *msg, size_t len)
{
	const uint8_t *msg8 = (uint8_t *)msg;
	while (len--) {
		crc = rf_crc32_8(crc, *msg8++);
	}
	return crc;
}
